That makes no sense. What "true reasons" do publishers have for DRM that aren't fundamentally financial?
1. Monopolistic lock-in. DRM is more than often used to control the market. It happened with Apple in the past, and was one of the key reasons that music publishers realized that being DRM-free is actually better for them.
This reason also includes DRM derivatives like DMCA-1201 and the like. It's all about control (over the markets, over users and etc.).
2. Covering one's incompetence. DRM is used to justify failing sales (i.e. when execs are questioned about why the product performs poorly, they say "Pirates! But worry not - we put more DRM in place").
3. Ignorance and / or stupidity (many execs have no clue and might believe that DRM actually provides some benefit). This type can be called DRM Lysenkoism.
None of these reasons are valid, all of them are crooked and anti-user, but they are often present in various combinations.
How does this benefit the publisher? They already have a exclusive rights to whatever particular movie you're watching.
When publishers realize that monopoly falls to some other hands, they quickly become sober and find common sense. When monopoly remains theirs, they pretend that DRM is needed for other reasons.